Since 1999, he has wired the helmets of about 700 college football players with accelerometers to study what kinds of hits result in concussions, which kinds of players get them, and what the long-term consequences of those brain injuries can be. He was among the first to find a strong link between multiple concussions and later dementia, depression and memory and intellectual deficits that often lead to Alzheimer’s disease.

When a 2005 report prepared for the NFL asserted that a player who had sustained a concussion could safely be returned to play on the same day, Guskiewicz begged to differ. In an interview on National Public Radio, he suggested that those drafting the NFL report “are more interested in trying to protect the game or the league rather than taking a more responsible approach.”

But by 2010, a lot had changed. A mountain of research — much of it by Guskiewicz but also by Boston University's Center for the Study of Traumatic Encephalopathy — had made clear even to the most hard-core football fans that concussions could not just be “shaken off.” The military’s experience with widespread trauma among troops in Iraq and Afghanistan, and numerous cases of suicides and dementia among recently retired football heroes, underscored that “getting your bell run” several times was likely to have long-term repercussions.

And so in 2010, when NFL Commissioner Roger Goodell offered Guskiewicz a seat on the NFL'sHead, Neck and Spine Committee and asked him to be chairman of the NFL’s panel on safety equipment and playing rules, Guskiewicz said yes.

Both in his work with the NFL and as a newly anointed MacArthur “genius,” Guskiewicz has a lot at stake. In addition to the 700-plus college athletes he tracks in his database and the thousands of retired athletes whose concussion experiences he has culled, Guskiewicz has his son Adam, an 11-year-old Pop Warner player who weekly suits up in the North Carolina colors for the Orange County (N.C.) Tar Heels.

Guskiewicz’s first job out of college was with the Pittsburgh Steelers, and he’s passionate about football. Three of his four children have played football, and Guskiewicz has coached Pop Warner teams for five of the last six years.

Guskiewicz says his friends think he’s “crazy” to let his son engage in a sport whose physical toll he has done so much to tally. “But they’re half-joking,” he adds. “Their comfort level is increased because I’m doing this work: Their kids are out there too.”

In fact, Guzkiewicz says he hopes to use some of the MacArthur prize money to continue research on concussion prevention through “behavior change,” and by teaching concussion prevention to the youngest players.

“It’s going to take more than a helmet change” to prevent concussions, he says. Players are going to need to develop blocking and tackling techniques that are safer — and the earlier they start, the more entrenched a new culture of safety will take hold in football, he says. His research can uncover patterns in a player’s movements that may contribute to his risk, and postgame films (whether at the Pee Wee or Pro level) can be used to teach a player better, safer playing techniques and postures, he says. The result could be fewer concussions and lower risk of depression and dementia in the years following their time on the gridiron.

At the University of North Carolina, Guskiewicz also is studying whether supplemental Omega-3 fatty acids — particularly the component DHA — may help protect retired NFL players from developing dementia or its early signs. And along with researchers from the UCLA Harbor Medical Group and John Wayne Cancer Institute in Santa Monica, Guskiewicz is exploring whether concussions and less forceful blows to the head may have damaged the pituitary glands of former NFL players, causing hormonal changes that could lead to hormonal disturbances, loss of muscle tone and premature aging, depression and sleep disruption.

“It’s a complex injury,” Guzkiewicz said of concussions in an interview. “No two concussions are the same. It’s like piecing together a puzzle. And we’re going to have to study a lot of concussions for us to get a clearer picture of the answer.”